L1520 Support ATT HD Voice?

In looking on the ATT site & coverage maps, they show HD Voice coverage in my area and they say it requires both parties to have a ATT HD voice compatible phone. When checking the list of supported phones, only the HTC One (M8) is listed for Windows Phones.
Does anyone know if the L1520 is HD voice compatible? If not, will it be with an OS/FW update?

VoLTE is supported in 8.1 Update 1. It's just not available yet on the 1520. It's possible this is a reason for AT&T's delay in rolling out Denim. Typically, software features do not receive heavy scrutiny or long testing periods. It is when changes occur within the network drivers and software that they thoroughly test updates. The Snapdragon 800 is VoLTE capable, and the 1520 has the noise-cancelling mics and software to support VoLTE and HD Voice (which, technically, does not refer to VoLTE but rather to the AMR-WB and EVRC-WB (wideband) voice codecs for GSM and CDMA based networks respectively). I suspect we should see VoLTE enabled in AT&T's Denim update for the 1520.

the rep did not answer the question and no the 1520 does not support HD VoLTE. Also feature must be deployed in selected markets to work- and must be using compatible device for both caller and receiver. iPhone 6 was touted to have HD voice calling as well as the newer Samsung Galaxys and HTC ONE M8 Windows. I havent read anywhere that Nok Lumia 1520 was capable of it.

VoLTE is supported in 8.1 Update 1. It's just not available yet on the 1520. It's possible this is a reason for AT&T's delay in rolling out Denim. Typically, software features do not receive heavy scrutiny or long testing periods. It is when changes occur within the network drivers and software that they thoroughly test updates. The Snapdragon 800 is VoLTE capable, and the 1520 has the noise-cancelling mics and software to support VoLTE and HD Voice (which, technically, does not refer to VoLTE but rather to the AMR-WB and EVRC-WB (wideband) voice codecs for GSM and CDMA based networks respectively). I suspect we should see VoLTE enabled in AT&T's Denim update for the 1520.

VoLTE is supported in 8.1 Update 1. It's just not available yet on the 1520. It's possible this is a reason for AT&T's delay in rolling out Denim. Typically, software features do not receive heavy scrutiny or long testing periods. It is when changes occur within the network drivers and software that they thoroughly test updates. The Snapdragon 800 is VoLTE capable, and the 1520 has the noise-cancelling mics and software to support VoLTE and HD Voice (which, technically, does not refer to VoLTE but rather to the AMR-WB and EVRC-WB (wideband) voice codecs for GSM and CDMA based networks respectively). I suspect we should see VoLTE enabled in AT&T's Denim update for the 1520.

Its actually there in the settings, but hidden by the registry. I will play around with mine and see if I he HD working

Just to follow up, I was able to get it to show the VoLTE toggle but I can't actually get it to turn on. See attached pictures. If you're wondering my method, its the old Windows Insiders app proxy trick that was patched a few weeks back. I have purposely not updated the app, so should be able to continue writing to the registry if there are other keys you guys want me to test